Michelin a1 airstop butyl road bike tubeairstop butyl tubes answer the needs of everyday cyclists for economical high quality inner tubes in each size airstop butyl tubes offer excellent puncture resistance and the consistently high quality for which michelin is famous please note 18 25c for stock 63726features 700x18 23c valve type a1 unthreaded 40mm presta valve 96g 52mm presta valve 98gbuymichelin wheels tyresfrom chain reaction cycles the worlds largest online bike store